GR6-M
DraftDescription
GR6-M is a stable Cone 6 floating blue glaze formulated with a Ravenscrag Slip and frit base. It serves as an alternative to traditional Gerstley Borate-based floating blue recipes, eliminating issues
Original Author
Tony Hansen
Usage Instructions
GR6-M is a stable Cone 6 floating blue glaze formulated with a Ravenscrag Slip and frit base. It serves as an alternative to traditional Gerstley Borate-based floating blue recipes, eliminating issues related to slurry gelling, inconsistent raw materials, high thermal expansion, and blistering. The base utilizes a blend of raw and roasted Ravenscrag Slip (typically 40:39 ratio) to optimize slurry rheology, shrinkage, and drying characteristics. This glaze exhibits significant rutile-driven variegation, crystalline development, and opalescence. It is effective on both buff stoneware and porcelain, though visual results vary based on clay body iron content and glaze thickness. While it produces strong blue coloration without requiring specific cooling schedules, a drop-and-hold cooling cycle (e.g., C6DHSC) is recommended to minimize surface defects and enhance surface quality. The slurry should be maintained at a specific gravity of 1.43–1.45 to ensure proper application thickness and prevent excessive running. Firing above Cone 6 increases melt fluidity, which enhances crystallization but requires caution regarding glaze runoff.